PASE) Velen: 
PTERINOPECTEN SPIO! -2 sess sec aeise se elec seer eee eis emine eats eee ate ee eee erate ete 
Fig. 1. Left valve,in which the surface has been largely removed, leaving the radiating 
costs and concentric lines in strong relief. Natural size. 
la. Left valve, on which the concentric lines are faintly defined. Natural size. 
MAGRODON; TRUNGATUB < se a me ww cremate mm imie emia nm mlm walt lal lille alli 
Fig. 2. Left valve, enlarged to nearly three diameters. 
PLEUROPHORUS: MBEKI co<- sees ey ele coe ele ciste mie ccleaner terete sine ester ee tha rt 
Fig. 3. Cast of left valve. Natural size. 
STREBEOPRTERIA. SUMIEIS ace. ose cies ee l= ma eae alee eaten la a tera anti oleae ee 
Fig. 4,4). Right valves. Natural size. 
4a, 4c. Left valves. Natural size. 
4d. Finely striated left valve. See plate xix, fig.7. 
PTY CHOPTERIA-PROTORORME) 222 :2 = coeias sae eens Sen oat ea Seen eae ee eee eae eee eee 
Fig. 5. Left valve. Natural size. 
AVICULOPRECDENDINTOENSIS( sca = njatac a= melee ne oe lesiatete te ler ale ere eet tet etal te el 
Fig. 6. Left valve. Natural size. 
(Oioin@anfomony Jeli eWQUiiscom Soameo soocoo yoasee Soo som en DoS HOoca Soaa ss ene sce sos escasoneSs 
Fig. 7. Cast of a large right valve. Natural size. 
7a. A small right valve. 
7b. A large left valve. Natural size. 
7c. Enlargement of the surface to show fine concentric striw crossing the radiating 
plications. 
AVICULOPEGTEN) PEROCGIDENS wca- ts anicinasicten saab are ese see Sait eee eee eee eee 
Fig. 8. Left valve. Natural size. 
PTERINOPECTENDHOOSAGENSIS 22m ]o cian cnices ef anno oo ee oe teeee ene eaten See 
Fig. 9. Left valve. Natural size. 
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